A few times during Sunday’s Ravens-Browns game, the officials called an illegal formation penalty because “the tight end was covered up.”

CBS analyst Rich Gannon was too busy dogging Browns quarterback Brandon Weeden to explain what that means. No, it’s not one of those uniform violations, though maybe in today’s NFL, some players might consider it worthy of a flag when a tight is wearing long sleeves and not showing off the guns.

Here’s an explanation we found from a 2004 article in the Chicago Tribune in which former NFL official Jerry Markbreit answered officiating questions:

“Under NFL rules, players are numbered for eligibility. Tight ends and wide receivers must be on the end of the line of scrimmage in order to be an eligible pass receiver. If a wide receiver is on the line of scrimmage and a tight end is inside of him, an illegal formation has occurred because another eligible has covered the eligible tight end. The formation would be legal if the wide receiver would drop off of the line of scrimmage so that he is not in a direct line with the tight end.”

In other words, the fault lies with the wide receiver, who needs to line up behind the line of scrimmage.

And as a bonus, here is likely the funniest thing ever written about illegal formations, from The Onion.